BALUNLESS TEST FIXTURE
A test fixture and method of its use are disclosed. The test fixture includes a test fixture frame including a first test fixture mount having a first test head mounted thereon, the first test head slidable along a first axis, and a second test fixture mount having a second test head mounted thereon that is slidable along a second axis perpendicular to the first axis. The test fixture further includes a first test plate holder mounted to the first test head and including a clamping mechanism, as well as a probe mounting plate mounted to the first test plate holder and retained by the clamping mechanism and including a plurality of radially-disposed probe receptacles. The test fixture includes a plurality of probe assemblies received in corresponding probe receptacles, each including a probe extending at least partially through the probe mounting plate, each electrically connecting to a design under test.
This application claims priority to U.S. Patent Application Ser. No. 61/909,147 filed on Nov. 26, 2013, the disclosure of which is incorporated herein by reference in its entirety.
TECHNICAL FIELDThe present application relates generally to a testing feature for networking equipment, and in particular to a balunless test fixture useable to test communication or networking equipment in twisted pair systems.
BACKGROUNDInternational standard ISO/IEC 11801 specifies general-purpose telecommunication cabling systems (structured cabling) that are suitable for a wide range of applications (analog and ISDN telephony, various data communication standards, building control systems, factory automation). The ISO/IEC standard covers both balanced copper cabling and optical cabling.
The standard defines several classes, or categories, of twisted-pair copper interconnects, which differ in the maximum frequency for which a certain channel performance is required. For example, category 5e utilizes frequencies up to 100 MHz, while category 6 utilizes frequencies up to 250 MHz. Category 6a utilizes frequencies up to 500 MHz, and category 7 uses frequencies of up to 1 GHz.
Telecommunication cabling systems, when implemented using electrical signals, utilize twisted pair wiring and electrical connectors to form communication channels between computing systems, routers, or other telecommunications and networking equipment. The wiring, formed as cables, as well as the electrical connectors, is required to meet electrical performance criteria set by such ISO standards. When telecommunications equipment, including telecommunications connectors, is manufactured, such equipment is typically tested to ensure compliance with electrical performance characteristics.
Existing systems that are used to test the electrical performance of twisted pair connectors or other networking devices typically use a test station that transmits electrical signals to the design under test, and measures the resulting electrical performance of that design. Such systems generally include a balun, which is a type of electrical transformer that converts differential electrical signals to single-ended (e.g., grounded) electrical signals, and vice versa. Such baluns are used in test fixtures to translate test signals to differential signals for transmission through the networking equipment to test its performance.
As signal frequencies increase, use of baluns increasingly becomes problematic. This is because the baluns included in such circuitry introduce some signal degradation (e.g., crosstalk and common-mode effects) leading to signal loss. Although this is not a substantial effect at lower frequencies and within more generous signal loss thresholds available in category 5, 5e, 6, or even 6a frequencies, when signal frequencies are at 1 GHz or higher, the signal degradation attributable to the balun represents a greater proportion of the overall loss in the test circuit. This is both because of the increased signal degradation attributed to the balun at high frequencies, as well as the increased performance requirements of such high frequency standards. In either case, use of baluns to convert between single-ended and differential signals can obscure the actual performance characteristics of the networking equipment design under test.
For these and other reasons, improvements are desirable.
SUMMARYIn accordance with the following disclosure, the above and other issues are addressed by the following:
In a first aspect, a test fixture for electrical equipment includes a test fixture frame including a first test fixture mount having a first test head mounted thereon, the first test head slidable along a first axis, and a second test fixture mount having a second test head mounted thereon, the second test head slidable along a second axis perpendicular to the first axis. The test fixture further includes a first test plate holder mounted to the first test head, the first test plate holder including a clamping mechanism, as well as a probe mounting plate mounted to the first test plate holder and retained by the clamping mechanism, the probe mounting plate including a plurality of radially-disposed probe receptacles. The test fixture also includes a plurality of probe assemblies received in corresponding probe receptacles, each of the probe assemblies including a probe extending at least partially through the probe mounting plate, each probe electrically connecting to a design under test.
In a second aspect, a method of testing electrical performance of an electrical connector is disclosed. The method includes mounting a probe mounting plate to a test plate holder retained by a test head of a test fixture mount, the probe mounting plate including a plurality of radially-disposed probe receptacles having a plurality of probe assemblies received therethrough, each probe assembly including a coaxial probe. The method also includes mounting a probe plate to a termination plate and the probe mounting plate, the probe plate having a design under test mounted thereto, wherein mounting the probe plate and termination plate to the probe mounting plate electrically connects the design under test to the coaxial probes of the plurality of probe assemblies. The method further includes clamping the probe plate, termination plate, and probe mounting plate to the test plate holder using a slidable clamping mechanism. The method includes testing electrical performance of the design under test based on signals sent or received via the probe assemblies.
In a third aspect, a test fixture for testing signal performance of a twisted pair connector is disclosed. The test fixture includes a test fixture frame including first and second test fixture mounts having first and second rest heads, respectively, which are positioned and slideable along perpendicular axes. The test fixture includes a first test plate holder mounted to the first test head and including a clamping mechanism, as well as a probe mounting plate mounted to the first test plate holder and retained by the clamping mechanism, the probe mounting plate including a plurality of radially-disposed probe receptacles. The test fixture also includes a plurality of probe assemblies received in corresponding probe receptacles, each of the plurality of probe assemblies, each of the probe assemblies including a probe extending at least partially through the probe mounting plate, each probe electrically connecting to an electrical connection of a twisted pair connector. The test fixture further includes a second test plate holder mounted to the second test head and including a second clamping mechanism, as well as a second probe mounting plate mounted to the second test plate holder and retained by the second clamping mechanism, the second probe mounting plate including a plurality of radially disposed probe receptacles. The test fixture includes a plurality of probe assemblies received in corresponding probe receptacles of the second probe mounting plate, each of the probe assemblies including a probe extending at least partially though the second probe mounting plate and electrically connecting to the twisted pair connector.
Various embodiments of the present invention will be described in detail with reference to the drawings, wherein like reference numerals represent like parts and assemblies throughout the several views. Reference to various embodiments does not limit the scope of the invention, which is limited only by the scope of the claims attached hereto. Additionally, any examples set forth in this specification are not intended to be limiting and merely set forth some of the many possible embodiments for the claimed invention.
In general the present disclosure relates to a balunless test fixture, such as could be used to test communications or networking equipment used in twisted pair systems. The test fixture features described herein provide for a configurable, adjustable test fixture that is adaptable to a variety of types of designs under test, such as connectors (e.g., RJ-45 plugs, jacks, or combinations thereof), as well as crosstalk compensation circuits, or other types of connectors or cabling to ensure its compliance with relevant ISO/IEC standards. In particular, the present disclosure describes a test fixture that avoids use of baluns and therefore is operable at frequencies up to an exceeding 1 GHz without electrical interference caused by such baluns obscuring the performance of the design under test.
As illustrated in
In the embodiment shown in
In the embodiment shown, a first test head 20 is mounted to the first chassis 15, and a second test head 21 is mounted to the second chassis 16. Each of test heads 20, 21 include a pivotable body 22, 23, respectively, extending upwards from respective base plates 24, 25 mounted to the respective chassis 15, 16, to accommodate different orientations or configurations of equipment to be tested.
Each of the test heads 20, 21 are configured to receive a test plate holder 30 mounted thereto. The test plate holder 30 generally is a rectangular-shaped device that can be mounted to the body 22, 23 of one of the test heads 20, 21, and includes a circular cutout at which one or more test plates (e.g., including a probe mounting plate, a termination plate, a probe plate, a load plate, or a calibration plate) can be mounted. The test plate holder 30 includes a clamp 32, shown as a slidable clamp affixed in place by a screw-down clamp, which is used to retain any such test plates in place during operation of the test fixture.
In addition, each of the test heads 20, 21 are configured to include a positional adjustment mechanism 34 useable to control a lateral position of the test plate holder 30. In example embodiments, the test plate holder 30 can be screwed to a mounting bracket extending from the body 22, 23 of one of the test heads 20, 21, and which is movably by way of the positional adjustment mechanism 34. In the embodiment shown, the positional adjustment mechanism 34 includes a dial adjustment however, in alternative embodiments, different types of positional adjustment mechanisms can be used. As illustrated in
Referring now to
In addition to the clamp 32 retention mechanisms 36 can be included on the plate 31 near the opening sized to receive test plates. The retention mechanisms can include, for example, a rotatable partial disk that can be rotated when a disk is present such that a rounded edge of the partial disk engages a test plate (e.g., as seen in
Still referring to
Specifically referring to
As seen in
As seen in
When mounted to the test plate holder 30, the probe mounting plate 40 is rotatable to any of a plurality of fixed rotational positions. In particular, and referring back to
As seen in
Referring to
In example embodiments, the probe assemblies have a three amp current rating, as well as 50 Ohms of nominal impedance. Probe tips 102 form an SMA termination at the electrode position, and can be constructed from a gold-plated brass or other equivalent resilient, conductive metallic material.
As seen in
Referring to
The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.
Claims
1. A test fixture for electrical equipment, the test fixture comprising:
- a test fixture frame including: a first test fixture mount having a first test head mounted thereon, the first test head slidable along a first axis; and a second test fixture mount having a second test head mounted thereon, the second test head slidable along a second axis perpendicular to the first axis;
- a first test plate holder mounted to the first test head, the first test plate holder including a clamping mechanism;
- a probe mounting plate mounted to the first test plate holder and retained by the clamping mechanism, the probe mounting plate including a plurality of radially-disposed probe receptacles;
- a plurality of probe assemblies received in corresponding probe receptacles, each of the probe assemblies including a probe extending at least partially through the probe mounting plate, each probe electrically connecting to a design under test.
2. The test fixture of claim 1, further comprising:
- a second test plate holder mounted to the second test head, the second test plate holder including a second clamping mechanism;
- a second probe mounting plate mounted to the second test plate holder and retained by the second clamping mechanism, the second probe mounting plate including a plurality of radially disposed probe receptacles;
- a plurality of probe assemblies received in corresponding probe receptacles of the second probe mounting plate, each of the probe assemblies including a probe extending at least partially though the second probe mounting plate and electrically connecting to the design under test.
3. The test fixture of claim 2, wherein the design under test comprises an electrical connection including a plug and a jack.
4. The test fixture of claim 1, wherein the clamping mechanism is slidable between retaining and retracted positions, and is affixable in place by a screw.
5. The test fixture of claim 1, further comprising a calibration plate mountable to the probe mounting plate and useable to calibrate measurements of electrical characteristics of the test fixture.
6. The test fixture of claim 1, further comprising a termination plate positioned on the probe mounting plate, the termination plate used to retain the design under test.
7. The test fixture of claim 6, wherein the design under test is positioned on a load plate having common electrical characteristics to a calibration plate.
8. The test fixture of claim 7, wherein the design under test includes a crosstalk compensation circuit.
9. The test fixture of claim 6, further comprising a probe plate mounted to the probe mounting plate, the probe plate including a plurality of electrical pads for connection of the design under test thereto.
10. The test fixture of claim 9, wherein the termination plate further includes one or more contact probes electrically connectable to the electrical pads of the probe plate.
11. The test fixture of claim 1, wherein each probe comprises a coaxial test cable probe.
12. The test fixture of claim 1, wherein the probe mounting plate includes a plurality of probe assembly retention clamps used to retain the probe assemblies in the corresponding plurality of radially-disposed probe receptacles.
13. The test fixture of claim 1, wherein the probe mounting plate is rotatable to a plurality of discrete positions when mounted to the first test plate holder.
14. The test fixture of claim 1, wherein the first test fixture mount includes a first vertical positioner useable to adjust a vertical position of the first test plate holder, and the second test fixture mount includes a second vertical positioner useable to adjust a vertical position of the second test plate holder.
15. A method of testing electrical performance of an electrical connector, the method comprising:
- mounting a probe mounting plate to a test plate holder retained by a test head of a test fixture mount, the probe mounting plate including a plurality of radially-disposed probe receptacles having a plurality of probe assemblies received therethrough, each probe assembly including a coaxial probe;
- mounting a probe plate to a termination plate and the probe mounting plate, the probe plate having a design under test mounted thereto, wherein mounting the probe plate and termination plate to the probe mounting plate electrically connects the design under test to the coaxial probes of the plurality of probe assemblies;
- clamping the probe plate, termination plate, and probe mounting plate to the test plate holder using a slidable clamping mechanism; and
- testing electrical performance of the design under test based on signals sent or received via the probe assemblies.
16. The method of claim 15, further comprising:
- mounting a second probe mounting plate to a second test plate holder retained by a second test head of a second test fixture mount oriented perpendicularly to the test fixture mount, the second probe mounting plate including a plurality of radially-disposed probe receptacles having a plurality of probe assemblies received therethrough, each probe assembly including a coaxial probe;
- mounting a second probe plate to a second termination plate and the second probe mounting plate, the second probe plate electrically connected to the design under test such that the second probe mounting plate electrically connects the design under test to the coaxial probes of the plurality of probe assemblies associated with the second probe mounting plate;
- clamping the second probe plate, second termination plate, and second probe mounting plate to the second test plate holder using a second slidable clamping mechanism.
17. The method of claim 16, further comprising adjusting a vertical and horizontal position of the first and second test heads to align with a design under test.
18. A test fixture for testing signal performance of a twisted pair connector, the test fixture comprising:
- a test fixture frame including: a first test fixture mount having a first test head mounted thereon, the first test head slidable along a first axis; and a second test fixture mount having a second test head mounted thereon, the second test head slidable along a second axis perpendicular to the first axis;
- a first test plate holder mounted to the first test head, the first test plate holder including a clamping mechanism;
- a probe mounting plate mounted to the first test plate holder and retained by the clamping mechanism, the probe mounting plate including a plurality of radially-disposed probe receptacles;
- a plurality of probe assemblies received in corresponding probe receptacles, each of the plurality of probe assemblies, each of the probe assemblies including a probe extending at least partially through the probe mounting plate, each probe electrically connecting to an electrical connection of a twisted pair connector;
- a second test plate holder mounted to the second test head, the second test plate holder including a second clamping mechanism;
- a second probe mounting plate mounted to the second test plate holder and retained by the second clamping mechanism, the second probe mounting plate including a plurality of radially disposed probe receptacles;
- a plurality of probe assemblies received in corresponding probe receptacles of the second probe mounting plate, each of the probe assemblies including a probe extending at least partially though the second probe mounting plate and electrically connecting to the twisted pair connector.
19. The system of claim 18, wherein the first probe plate is mounted to a twisted pair electrical jack, and wherein the second probe plate is mounted to a twisted pair electrical plug mated to the twisted pair electrical jack.
20. The system of claim 19, wherein each of the probes comprise coaxial probes that electrically connect to test pads of the first and second probe plates, respectively, via contact probes of the first and second termination plates.
Type: Application
Filed: Nov 26, 2014
Publication Date: Jan 5, 2017
Patent Grant number: 10545173
Inventors: Gordon John WHITE (Gloucester, Gloucestershire), Bernard Harold HAMMOND, Jr. (Cheltenham, Gloucestershire), Ian Robert GEORGE (Churchdown, Gloucestershire)
Application Number: 15/039,836